Color photography



Patented Jan. 6, 1942 UNITED STATE Gustav Wilmanns, Wolfen, KreisBitterfeld,'and

Wilhelm Schneider, Dessau, Ge

rmany, assignors. by memo assignments, to General Aniline a FilmCorporation, New York, N. Y., poration Delaware No Drawing. ApplicationJanuary c, 1938, Serial No. 183,588. In Germany January 21, 1937 1 3Claims.

Our present invention relates to color photography and more particularlyto a process of colorforming development.

Inthe production-o1 multi-color pictures the exposed layers haveheretofore been developed directly or by reversal development to producea positive or negative silver image which, after fixing, has beenconverted into a silver salt and l the colored image has then beenformed b a color forming developer. In this methodlay which do notcontain dyestufl components may be used and the latter have beenintroduced into the developer for producing the colored image. Fordeveloping the various color images in their several layers a largenumber of treating and developing operations is necessary. so that themethod is very tedious. v

'It is therefore one of the objects of this invention to provide acomparatively simple color developing process which,however, enables theoperator to make necessary corrections in the color' shades and toeliminate undesirable color strains.

Further objects of this inventionwill become apparent from the'detaileddescription following hereinafter.

The invention is concerned with a process in which there is useda'multi-layer photographic material containing in the several layers,the suitable dyestuflf components for thcomponent pictures and thecorrect coloring is controlled first by simple or reversal developmentin the several layers to produce component silver imagesandthen, afterfixing and converting the silver into a silver salt, further developingwith the color forming developers. As compared with the directdevelopment of the color image in which causes a corresponding change incolor tints during the subsequent color forming development.

The developing solutions to be used may either contain differentsubstances suitable for color I forming development or the speed ofaction of one and the same .or even diflerent developers may be variedby additions.

Moreover, it is possible .to correct tint oi! the image by treatmentwith acolor developer which-at the same time contains a dyestuiicomponent which produces a color which 'is partly lacking orinsufiicient in the finished color picture. Since in this case theaction of the color forming developer is not limited to any particularlayer, the method lends itself only to a comparatively smallcompensation of the color tint.

As dyestuff formers for the silver halide emulsion layers there may beused with advantage dyestufi components which are fast to diflusion withrespect to the binding agent of the emulsion owing to the presence ofcertain radicals in their molecule. As described in U. S. Patent2,179,238, groups may be introduced into the color components whichimpart to the molecule of the color .lormer a substantive character. As'described in U. 8. Patent 2,178,612 the dyestufi components may be madefast to diffusion by introducing into their molecule radicals of highly.

polymeric carboxylic acids or their derivatives.

Moreover, dyestufl components become fast to difiusion when as describedin U. 8. Patent 2,186,849, there is introduced thereinto an allwhich thenumber of necessary process steps is smaller this new method has thegreat advantage oi permitting control of the color tints in fulldaylight. Thus faulty reproduction may without difilculty be avoided andmatters of personal preference in the color reproduction may be takeninto consideration. For example, in printing a complementary colornegative onto a multilayer positive material containing component's anundesirable color strain in the positive may be completely removed bytreating this bleached-out positive in succession with difierent colorformphatic carbon-chain of more than 5 carbon atoms, or, as described inU. S. Patent 2,179,244 polypeptide radicals, or, as described in U. 8.Patent 2,186,732 a carbohydrate radical, or, as

' described in U. S.' Patent 2,186,733 the radical of a natural resin,or, as described in U. S.'Patent 2,186,851 a sterol radical.Furthermore, dyestufi componentsfast to diffusion are also ""obtalnedwhen, asdescrlbed in U. 8. Patent 2,186,- 784 the molecules of thedyestuff components are linked together to yield a chain-like molecule.It is also possible to produce dyestufl components fast to diffusion inmanner described in U. 8.

Patent 2,179,228, in which the dyestufl picture is produced byazo-coupling. Generally such dyestud components are fast to diffusionwhich are substituted by radicals of comparatively high molecular weight(2,179,239).

As developing agents there'may-be used for example the substancesdescribed in U. 3. Patents Nos. 1,102,028; 2,146,040: 2,163,781;2,124,612;

2,108,243; 2,122,599; 2,163,826 and 2,163,166.

The following examples illustratethe inven- .tion:'

Example 1.A multi-layer film, in which the first silver halide emulsionis pan-chromatically the color sensitized and comprises a colorcomponent which yields on color forming development a blue image, andthe second layer is sensitized for green and comprises a dyestuflcomponent which yields a red image on color forming development and thethird layer is not sensitized and comprises a dyestufi. component whichon color forming development yields a yellow image, is ex-' posed andthereafter developed in normal man.-

. bleached by a Farmer's Reducer whereby the pure three-color imageremains. As compared with a development in which the first developeryields the dyestufl, the present method has the advantage that anydesired usual black-andwhite developer may be used as the firstdeveloper and in this manner an essentially higher sensitivity attained,since it is known that a color forming developer is less powerful in itsdeveloping effect than are the usual black-andwhite developers.

Example 2.If a film treated, for example, in a manner analogous to thatdescribed in Example 1 shows an undesirable color strain produced may beby insufficiency of one of the component colors, then the defect in thefilm may be eliminated by a subsequent treatment. The silver producedsimultaneously with the dyestufl formation is bleached out and a colordeveloper which contains a dyestufi! component for the particular colorshade lacking in the picture, is employed. For example,'if the film,owing to the lack of red, appears too greenish, a developer will be usedwhich in addition to the color forming agent, contains a red dyestufifcomponent, for instance grams per liter ofl-phenyl-3-methylfi-pyrazolone. If, owing to the lack of blue, the filmhas a yellow to reddish-appearance, then there is added to the developerinstead of a pyrazolone the corresponding quantity of naphthol. m y 5Example 3'.In cases where it can be foreseen that the finished colorfilm will show an undesirable color shade owing to the predominancereason will have a reddish strain, then there may be used as adeveloper's solution of 8 grams per liter of 6-methyl-amino-3-toluldinemade alkaline with sodium carbonate. By this developer the tint of thecolor film produced will be shifted towards the green in comparison witha film developed with para-amino-dimethylaniline.

We claim: I

1. A process of producing photographic color pictures on multi-iayerphotographic material comprising a plurality of silver halide emulsionlayers containing dyestufi! components fast to diflusion, said dyestuffcomponents being capable of forming a dye in the places of thesilverpicture upon being contacted with -a color forming developer, whichprocess comprisesexposing said material to light, developing the latentimage thus formed with a black-andwhite developer, fixing thedevelopedpicture, reconverting the formed silver into -a silver salt capable ofbeing developed by a color-forming developer which would normally yielddyestui! images having undesired color strains, redeveloping s'aidsilver salt by means of a color forming developer while compensating forsuch undesired color strains by using a developer having the property ofshifting the color values to correct said color strains.

2. A process of producing photographic color pictures on multi-layerphotographic material 7 comprising a plurality of silver halide emulsionlayers containing dyestufl components fast to diffusion, said dyestui!components being sired depression of the unduly predominant colon.

of a certain colored light during exposure, this that the finished filmwill show a violet strain,

then this strain may be removed or profoundly modified by adding to thecolor developer 10 grams of aceto-acetic acid anilide per liter.

Example 4.-,-If it is known beforehand that the finished colored filmfor one reason or another will show acertain color strain, then it ispossible to counteract this color strain by using as a developer asubstance which in itself shifts the tint of the picture in a sensecomplementary to the undesired color strain which is If, for example, itis known that the film for some capable of forming a dye in the placesof the silver picture upon being contacted with a color formingdeveloper, which process comprisesexposing said material to light,developing the latent image thus formed witha black-and-white developer,fixing the developed picture, reconverting the formed silver 'into asilver salt capable of being developed, redeveloping said silver salt bymeans of a color forming developer containing a dyestuif component,capable of forming a dye with the oxidation product of the developercomplementary to the color previously determined to unduly predominatein the final picture, in an amount sufllcient to eifect the de- 3. Aprocess of producing photographic color pictures on a photographicmaterial comprising.

three superposed silver halide emulsion layers containing dyestuffcomponents fast to diffusion, said dyestuif components being capable offorming a dye in the places of the silver picture upon being contactedwith a color-forming developer, which process comprises exposing saidmaterial to light, developing the latent image thus formed with a blackand white developer, fixing the developed picture, reconverting theformed silver into a silver salt capableof being developed, redevelopingsaid silver salt by means of a colorforming developer, bleaching thesilver formed by development, determining any undue predominance of oneof the three subtractive colors in the three color picture thusproduced, and developing again with a color-forming developer containinga dyestufi' component capable of forming a dye with the oxidationproduct of-said color-forming developer complementary to the colorunduly predominant in said picture.

I .QUSTAV WILMANNS.

